Daniel is 4 times as old as Gabriela and is also 6 years older than Gabriela. How old is Daniel?
Explanation: We can use the given information to write down two equations that describe the ages of Daniel and Gabriela. Let Daniel's current age be $d$ and Gabriela's current age be $g$ $d = 4g$ $d = g + 6$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $d$ is to solve the second equation for $g$ and substitute that value into the first equation. Solving our second equation for $g$ , we get: $g = d - 6$ . Substituting this into our first equation, we get the equation: $d = 4$ $(d - 6)$ which combines the information about $d$ from both of our original equations. Simplifying the right side of this equation, we get: $d = 4d - 24$ Solving for $d$ , we get: $3 d = 24$ $d = 8$.